Microorganisms and plants have great potential for the degradation or detoxification of organic and metallic wastes in contaminated environments. One obstacle to the development of effective in situ bioremedial systems is our fundamental lack of understanding concerning the requirements, dynamics, and limitations on the functioning of degradative microorganisms in natural ecosystems such as soil. This includes limitations on indigenous microorganisms, as well as introduced genetically-modified microorganisms, and on the growth and functioning of plants and plant/microbe systems. Most ecological studies of remedial organisms have examined single isolates of bacteria or fungi; relatively little is known about the ecology of microbial consortia or the mutualistic association of remedial microorganisms with plants. Moreover, little is known about the limitations to bioremediation in complex systems which often contain more than one toxic organic chemical or heavy metal. This Project will act as the interface between basic genetic, biochemical, and physiological studies of degradative organisms and the application of these studies, specifically the bioremediation of contaminated soils. Specific aims of this project include: 1. Determining the environmental factors affecting the survival and activity of degradative microorganisms introduced into contaminated soil; 2. Investigating the important metabolic, ecological, and genetic interactions which influence the degradative activity of microbial consortia in contaminated soil and the rhizosphere; 3) Examining the effect of soil metals on bacterial populations present in contaminated systems; 4) Determining the potential for transfer of metals and organics into the food chain via plant uptake; and 5) Investigating the potential for soil remediation via plant uptake and transformation.